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247 lines
5.8 KiB
247 lines
5.8 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Access kernel memory without faulting -- s390 specific implementation. |
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* |
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* Copyright IBM Corp. 2009, 2015 |
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* |
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* Author(s): Heiko Carstens <[email protected]>, |
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* |
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*/ |
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#include <linux/uaccess.h> |
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#include <linux/kernel.h> |
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#include <linux/types.h> |
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#include <linux/errno.h> |
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#include <linux/gfp.h> |
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#include <linux/cpu.h> |
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#include <asm/ctl_reg.h> |
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#include <asm/io.h> |
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#include <asm/stacktrace.h> |
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static notrace long s390_kernel_write_odd(void *dst, const void *src, size_t size) |
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{ |
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unsigned long aligned, offset, count; |
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char tmp[8]; |
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aligned = (unsigned long) dst & ~7UL; |
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offset = (unsigned long) dst & 7UL; |
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size = min(8UL - offset, size); |
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count = size - 1; |
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asm volatile( |
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" bras 1,0f\n" |
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" mvc 0(1,%4),0(%5)\n" |
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"0: mvc 0(8,%3),0(%0)\n" |
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" ex %1,0(1)\n" |
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" lg %1,0(%3)\n" |
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" lra %0,0(%0)\n" |
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" sturg %1,%0\n" |
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: "+&a" (aligned), "+&a" (count), "=m" (tmp) |
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: "a" (&tmp), "a" (&tmp[offset]), "a" (src) |
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: "cc", "memory", "1"); |
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return size; |
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} |
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/* |
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* s390_kernel_write - write to kernel memory bypassing DAT |
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* @dst: destination address |
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* @src: source address |
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* @size: number of bytes to copy |
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* |
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* This function writes to kernel memory bypassing DAT and possible page table |
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* write protection. It writes to the destination using the sturg instruction. |
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* Therefore we have a read-modify-write sequence: the function reads eight |
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* bytes from destination at an eight byte boundary, modifies the bytes |
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* requested and writes the result back in a loop. |
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*/ |
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static DEFINE_SPINLOCK(s390_kernel_write_lock); |
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notrace void *s390_kernel_write(void *dst, const void *src, size_t size) |
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{ |
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void *tmp = dst; |
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unsigned long flags; |
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long copied; |
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spin_lock_irqsave(&s390_kernel_write_lock, flags); |
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if (!(flags & PSW_MASK_DAT)) { |
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memcpy(dst, src, size); |
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} else { |
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while (size) { |
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copied = s390_kernel_write_odd(tmp, src, size); |
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tmp += copied; |
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src += copied; |
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size -= copied; |
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} |
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} |
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spin_unlock_irqrestore(&s390_kernel_write_lock, flags); |
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return dst; |
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} |
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static int __no_sanitize_address __memcpy_real(void *dest, void *src, size_t count) |
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{ |
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register unsigned long _dest asm("2") = (unsigned long) dest; |
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register unsigned long _len1 asm("3") = (unsigned long) count; |
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register unsigned long _src asm("4") = (unsigned long) src; |
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register unsigned long _len2 asm("5") = (unsigned long) count; |
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int rc = -EFAULT; |
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asm volatile ( |
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"0: mvcle %1,%2,0x0\n" |
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"1: jo 0b\n" |
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" lhi %0,0x0\n" |
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"2:\n" |
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EX_TABLE(1b,2b) |
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: "+d" (rc), "+d" (_dest), "+d" (_src), "+d" (_len1), |
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"+d" (_len2), "=m" (*((long *) dest)) |
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: "m" (*((long *) src)) |
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: "cc", "memory"); |
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return rc; |
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} |
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static unsigned long __no_sanitize_address _memcpy_real(unsigned long dest, |
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unsigned long src, |
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unsigned long count) |
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{ |
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int irqs_disabled, rc; |
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unsigned long flags; |
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if (!count) |
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return 0; |
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flags = arch_local_irq_save(); |
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irqs_disabled = arch_irqs_disabled_flags(flags); |
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if (!irqs_disabled) |
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trace_hardirqs_off(); |
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__arch_local_irq_stnsm(0xf8); // disable DAT |
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rc = __memcpy_real((void *) dest, (void *) src, (size_t) count); |
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if (flags & PSW_MASK_DAT) |
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__arch_local_irq_stosm(0x04); // enable DAT |
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if (!irqs_disabled) |
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trace_hardirqs_on(); |
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__arch_local_irq_ssm(flags); |
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return rc; |
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} |
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/* |
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* Copy memory in real mode (kernel to kernel) |
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*/ |
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int memcpy_real(void *dest, void *src, size_t count) |
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{ |
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int rc; |
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if (S390_lowcore.nodat_stack != 0) { |
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preempt_disable(); |
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rc = CALL_ON_STACK(_memcpy_real, S390_lowcore.nodat_stack, 3, |
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dest, src, count); |
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preempt_enable(); |
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return rc; |
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} |
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/* |
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* This is a really early memcpy_real call, the stacks are |
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* not set up yet. Just call _memcpy_real on the early boot |
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* stack |
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*/ |
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return _memcpy_real((unsigned long) dest,(unsigned long) src, |
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(unsigned long) count); |
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} |
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/* |
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* Copy memory in absolute mode (kernel to kernel) |
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*/ |
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void memcpy_absolute(void *dest, void *src, size_t count) |
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{ |
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unsigned long cr0, flags, prefix; |
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flags = arch_local_irq_save(); |
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__ctl_store(cr0, 0, 0); |
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__ctl_clear_bit(0, 28); /* disable lowcore protection */ |
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prefix = store_prefix(); |
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if (prefix) { |
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local_mcck_disable(); |
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set_prefix(0); |
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memcpy(dest, src, count); |
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set_prefix(prefix); |
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local_mcck_enable(); |
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} else { |
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memcpy(dest, src, count); |
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} |
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__ctl_load(cr0, 0, 0); |
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arch_local_irq_restore(flags); |
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} |
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/* |
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* Copy memory from kernel (real) to user (virtual) |
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*/ |
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int copy_to_user_real(void __user *dest, void *src, unsigned long count) |
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{ |
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int offs = 0, size, rc; |
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char *buf; |
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buf = (char *) __get_free_page(GFP_KERNEL); |
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if (!buf) |
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return -ENOMEM; |
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rc = -EFAULT; |
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while (offs < count) { |
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size = min(PAGE_SIZE, count - offs); |
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if (memcpy_real(buf, src + offs, size)) |
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goto out; |
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if (copy_to_user(dest + offs, buf, size)) |
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goto out; |
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offs += size; |
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} |
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rc = 0; |
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out: |
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free_page((unsigned long) buf); |
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return rc; |
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} |
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/* |
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* Check if physical address is within prefix or zero page |
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*/ |
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static int is_swapped(unsigned long addr) |
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{ |
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unsigned long lc; |
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int cpu; |
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if (addr < sizeof(struct lowcore)) |
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return 1; |
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for_each_online_cpu(cpu) { |
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lc = (unsigned long) lowcore_ptr[cpu]; |
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if (addr > lc + sizeof(struct lowcore) - 1 || addr < lc) |
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continue; |
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return 1; |
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} |
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return 0; |
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} |
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/* |
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* Convert a physical pointer for /dev/mem access |
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* |
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* For swapped prefix pages a new buffer is returned that contains a copy of |
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* the absolute memory. The buffer size is maximum one page large. |
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*/ |
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void *xlate_dev_mem_ptr(phys_addr_t addr) |
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{ |
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void *bounce = (void *) addr; |
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unsigned long size; |
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get_online_cpus(); |
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preempt_disable(); |
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if (is_swapped(addr)) { |
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size = PAGE_SIZE - (addr & ~PAGE_MASK); |
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bounce = (void *) __get_free_page(GFP_ATOMIC); |
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if (bounce) |
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memcpy_absolute(bounce, (void *) addr, size); |
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} |
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preempt_enable(); |
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put_online_cpus(); |
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return bounce; |
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} |
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/* |
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* Free converted buffer for /dev/mem access (if necessary) |
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*/ |
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void unxlate_dev_mem_ptr(phys_addr_t addr, void *buf) |
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{ |
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if ((void *) addr != buf) |
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free_page((unsigned long) buf); |
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}
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